Tseng G N, Robinson R B, Hoffman B F
Department of Pharmacology, College of Physicians and Surgeons, Columbia University, New York, New York 10032.
J Gen Physiol. 1987 Nov;90(5):671-701. doi: 10.1085/jgp.90.5.671.
The membrane potential and membrane currents of single canine ventricular myocytes were studied using either single microelectrodes or suction pipettes. The myocytes displayed passive membrane properties and an action potential configuration similar to those described for multicellular dog ventricular tissue. As for other cardiac cells, in canine ventricular myocytes: (a) an inward rectifier current plays an important role in determining the resting membrane potential and repolarization rate; (b) a tetrodotoxin-sensitive Na current helps maintain the action potential plateau; and (c) the Ca current has fast kinetics and a large amplitude. Unexpected findings were the following: (a) in approximately half of the myocytes, there is a transient outward current composed of two components, one blocked by 4-aminopyridine and the other by Mn or caffeine; (b) there is clearly a time-dependent outward current (delayed rectifier current) that contributes to repolarization; and (c) the relationship of maximum upstroke velocity of phase 0 to membrane potential is more positive and steeper than that observed in cardiac tissues from Purkinje fibers.
使用单微电极或吸管研究了单个犬心室肌细胞的膜电位和膜电流。这些肌细胞表现出被动膜特性和动作电位构型，类似于多细胞犬心室组织中所描述的。与其他心脏细胞一样，在犬心室肌细胞中：(a)内向整流电流在决定静息膜电位和复极化速率方面起重要作用；(b)河豚毒素敏感的钠电流有助于维持动作电位平台期；(c)钙电流具有快速动力学和大的幅度。意外发现如下：(a)在大约一半的肌细胞中，存在由两个成分组成的瞬时外向电流，一个被4-氨基吡啶阻断，另一个被锰或咖啡因阻断；(b)明显存在有助于复极化的时间依赖性外向电流（延迟整流电流）；(c)0期最大除极速度与膜电位的关系比在浦肯野纤维的心脏组织中观察到的更正向且更陡峭。
